Cancer is a large group of diseases characterized by uncontrolled cellular growth of, and invasion by, abnormal cells. If the spread is not controlled or checked, it results in death of the cancer patient. However, many cancers can be cured if detected early and treated promptly. The incidence of cancer is increasing.
Early detection of cancer greatly increases the potential for control. Detection of cancer in a localized or regional area, possibly with diagnosis early in the growth of the tumor, permits the use of more effective therapy, and improves the chance for recovery. Treatment by surgery, chemotherapy or radiation requires post-treatment monitoring to ensure that all vestiges of the malignant growth have been eliminated.
A number of tumor-associated metabolic products (markers) have been identified, some of which have been considered for use as tumor markers. Many of these tumor markers are uniquely associated with specific tumors. As a result, their presence can be used to reliably detect these tumors, making earlier, more reliable detection of the tumor possible. Some of the better known tumor markers are: carcinoembryonic antigen (CEA) for cancers of the colon, lung, stomach, and pancreas; alpha-fetoprotein (AFP) for testicular and liver cancers; and a tumor marker for breast cancer (CA15-3).
While some tumor markers have been identified, the number is very limited and directed at only a few forms of cancer. In addition, even if the number of individual tumor markers is expanded to include all forms of cancer, the routine diagnostic testing of patients would be very expensive and laborious since each form of cancer would require a separate test using each of the separate markers. The cost and time involved in such testing would preclude general screening of the population, therefore a form of testing is needed that would be most effective for the early diagnosis and treatment of malignancies before they become clinically manifest.
It is desirable that a test system is developed which is cost effective and which will detect any form of cancer in a single test. It is also desirable that such a test is not affected by background reactions which result from the source of the material tested and that the test is sensitive enough to detect the tumor marker at very early stages in the development of the tumor. It is also desirable that the test is simple to perform. It is also preferable that the test be performed on extracellular fluid samples which can be easily obtained in a doctor's office, or by the patient themselves, without the need for biopsy procedures.